We present the next-to-leading-order calculation of the partial decay widths of a Higgs boson decaying into four fermions in the Two-Higgs-Doublet Model, including a discussion of different renormalization schemes. We also comment on new developments in the renormalization of mixing angles. The calculation is implemented into the analysis tool Prophecy4f, and some sample results generated with the extension of Prophecy4f are shown.